This invention relates in general to vehicles, and in particular, to construction machinery such as earthmoving equipment.
More specifically, but without restriction to the particular use which is shown and described, this invention relates to a pivoting ejector assembly for a vehicle, such as a scraper or the like, for collecting and discharging material retained within the vehicle during use. The pivoting ejector assembly includes an ejector gate or member operably mounted for pivotal movement within the bowl of a scraper or the like. The ejector gate is adapted to sweep material collected in the bowl to a position for discharge therefrom, the operates in cooperation with a pivotally mounted elevator to allow a greater extent of movement of the ejector member for improved collection capacity and discharge of material. The pivoting ejector assembly, and elevator assembly, are controlled by a novel hydraulic circuit, attaining improved operation of both components during operation of the earthmoving equipment.
One type of construction machinery commonly used in earth moving operations is known as a scraper that utilizes a blade to engage the surface and dislodge earth material. The dislodged material is then carried by means of an elevator system for retention in a collection box known in the art as a bowl. After a scraping operation is completed, the earth material may be transported to a desired location and the contents of the bowl discharged. One common technique of discharging material collected in the bowl is through the use of a movable floor. In a bowl having a movable floor, at least a portion of the bowl floor moves from a closed position to an open position, permitting material to be dumped through a discharge opening.
In the dumping mode, the earth material is moved by a movable ejector member into the vicinity of the opening exposed by the movable floor. The ejector member is accordingly urged from a collection position, at which it serves as an upright wall of the bowl, to a discharge position to sweep or carry the material collected in the bowl to the discharge opening. A well known movable floor mechanism for scrapers employs floor mounted rollers to facilitate the movement between an open and closed position. The use of a roller support for such floors, however, requires constant and often tedious adjustment to maintain efficient operation of the scraper. In operation, hard substances, such as rocks and other solids, tend to lodge under the rollers and cause binding to interfere with the opening of the bowl to dump a load, or its subsequent closing to resume earth moving operations.
Another type of scraper employs a bowl having a fixed bottom and an open end, generally confronting the elevator. A fixed bottom bowl solves some of the operational problems associated with the movable floor technique, but also possesses its own shortcomings. For example, the inherent design of a bowl having a fixed floor requires that the ejector gate, in comparison to a movable floor bowl, move a greater distance to discharge material and at a fixed and flatter angle to avoid structural interference with the scraper elevator. Known ejector members, retained at fixed angles, must be of limited height to insure that their top portions do not strike the elevator during a dumping operation. This imposition of a limitation to the height of the ejector results in a reduction of the load capacity of the bowl in the retracted position of the ejector. Examples of prior art bowl assemblies suffering from the foregoing deficiencies are disclosed in U.S. Pat. No. 3,334,428 to Rezabek, U.S. Pat. No. 3,296,716 to Rezabek, et al., U.S. Pat. No. 3,462,859 to Hawk and U.S. Pat. No. 3,916,545 to Hochmann, et al.
The requisite movement of the ejector member in a bowl is generally effected by hydraulic cylinders controlled by a suitable hydraulic control circuit. The conventional control circuits of the prior art have been deficient in providing means to effectively prevent contact between the ejector and elevator during the discharge operation of the scraper. One recent type of ejector control circuit, attempting to avoid interfering contact between a fixed angle ejector member and an elevator, is disclosed in U.S. Pat. No. 3,977,100 to Boersma.